With development of information society, there is provided a higher requirement of storing and processing of information. A traditional information storage and process based on semiconductor industry approaches its physical limitation in terms of storage density and computing speed, so it becomes urgent to develop a new storage technology and information processing technology. Magnetic storage technology and spin-logic devices are paid much more attentions to due to their low power consumption and high operation speed.
In order to pursue a higher storage density, magnetic materials with strong perpendicular anisotropy and a large coercive force is widely used to a magnetic memory including a hard disk. However, a large perpendicular anisotropy and a large coercive force in turn lead to that it becomes difficult to write data based on a conventional magnetic head and a spin-transfer torque effect. Meanwhile, as another development direction of high density integration, multiple-valued storage and multi-valued logic calculation that can also be used in neuromorphic computing become very important. In the magnetic memory and spin-logic devices, since it is absent of a reliable means for magnetization operation, it is difficult for the multi-valued storage or the multi-valued logic operation which is based on the multi-domain magnetic state to be applied. Its main reason is that a process of forming magnetic domains in magnetic thin film is a random process, and the process of forming the magnetic domains is uncontrollable. Even under the same condition for forming the magnetic domains, such as introduction of defects, application of an external magnetic field or direct inletting of a large current or the like, it is difficult to get the same number of magnetic domains, the same volume of magnetic domains and the same position of the magnetic domain. From the view point of application, the magnetic film may be manufactured to be a microstructure having a characteristic dimension of several tens of nanometers to several tens of micrometers by utilizing nanofabrication technologies. However, when defects are introduced to samples having a characteristic dimension of several tens of nanometers to several tens of micrometers, currents are inlet into the samples or an external magnetic field is applied to the samples, the multi-domain states are still not able to be controlled since the uncontrollability of the magnetic domain is generally considered to be caused by a basic physical mechanism for forming the magnetic domain itself. Due to the uncontrollability of the multi-domain state, there is not yet an effective means to regulate the multi-domain state.
Therefore, it is very import to find a method for reliably regulating magnetic multi-domain states to effectively control these magnetic multi-domain stages in the application field.